Loud speaker



June 9, 1931. H. J. ROUND 1,809,571

1.6111) SPEAKER Filed Nov. 11, 1924 INVENTOR ESNRY J. ROUND Q4 ri%%'ATTORN EY Patented June 9, 1931 UNITED STATES, PATENT orrlcs HENRYJOSEPH ROUND, OF LONDON, ENGLAND, ASSIGNOR TO RADIO CORPORATION OFAMERICA, A CORPORATION OF DELAWARE LOUD SPEAKER Application filedNovember 11,1924, Serial No. 749,117, and in Great Britain November 19,1923.

The object of this invention is to provide an improved loud speaker.

According to this invention I mount upon an umbrella-like structureconsisting of radial ribs and stretchers a covering of paper, varnishedsilk or the like, and I provide means whereby the speech currents or thelike which are to be converted into sound waves produce a longitudinalmovement of the stick so that the covering is vibrated by the currents.

The invention is illustrated by the accompanying drawings in whichFigure 1 is a diagrammatic illustration of one form of my invention;

Figures 2 and 3 show respectively, a sectional view and a plan view of amodification ofmy invention; and

Figure 4 is a diagrammatic illustration of still another modification ofmy invention.

In Figure 1, A is a stick or rod which passes through the runner B andhas attached to it a plurality of spaced ribs C which are covered by amembrane, for example paper, and are connected b-y stretchers D to therunner B in the manner of an umbrella or parasol. The runner is pinnedor secured to the stick after the diaphragm is stretched. The stick Acarries the armature E of an electromagnet F through the coil of whichspeech currents or the like can be led. The currents in the coil of themagnet will cause the stick to move to and fro. This vibration will becarried through the stick and the stretchers to the ribs and from theseribs on to the membrane.

Preferably the covering is of such a size that it cannot be opened tosuch an extent as to make it flat, thus enabling the surface to be wellstretched.

As an alternative the stick may act as the core of a solenoid throughwhich the currents are passed.

The motion of the stick may, however, be obtained in various other ways,electrostatically, electromagnetically or by a magnetostriction device.a

Inplace of the stretchers being on the concave side they may be placedon the convex of the structure, the more so the lower tones predominate,and therefore that with a large structure of this kind it is preferableto employ a smaller one to prevent the loss of higher tones. Bothmembranes may be mounted on the same rod or stick. Figure 4 shows suchan arrangement where both the large membrane and the small membrane aremounted on the same rod.

Such an umbrella-like arrangement may also be employed to produce soundwhen the movements of the stick and stretchers are obtained mechanicallyinstead of electrically or magnetically.

For instance, a needle inserted in the stick at right angles thereto maybeactuated by a gramophone record.

In some cases I may dispense with the stretchers and use a flatstructure, with stretched wires as ribs connecting a fixed rim to acentre piece which takes the place of the stick and acts as the armatureof an electromagnet through the coils of which the currentsare passed.

I Such an arrangement is illustrated in Fig ures 2 and 3, Figure 2 beinga section and Figure 3 a plan.

The ribs C are connected each at one end to afixed rim G and at theother end to the armature E of the magnet F, varnished paper or silkbeing stuck on to the ribs.

Having described by invention what I claim is 1. In combination, aplurality of spaced strips, a membrane covering the strips, stretchersattached to the strips and means for actuatin the structure to re)roduce sound.

2. In a loud speaker, a plurality of ribs, a membrai'ie stretched uponsaid ribs, lJl'tlCQrv' tor reinforcing the ribs and means forreciprocating the assemblage formed by the ribs braces and memlnanc in aline 1 erpendicnlar to the general plane oi? the membrane.

3. In a loud speaker, a concave shaped membrane, ribs for spreading themembrane, stretchers :lior teusioning the ribs and means for vibratingthe membrane to reproduce sound.

4. In a loud speaker, a tympanum having a plurality of elements attachedtogether, the elements each consisting of a membrane stretched uponstretching ribs, braces for re inforcing the ribs and means forreciprocating said tympanum in a line perpendicular to the general planeof the membrane.

5. In a loud speaker, a series of intersecting ribs, a reciprocableelement terminated at the center of said series of intersecting ribs,braces attached to the reciprocable element and to the ribs, a membranefitted over the ribs, and means for reciprocating the reciprocablemember.

6. A loud speaker comprising a plurality of intersecting ribs, a membernormal to said. ribs at their point of intersection, a brace attached toeach rib and to said normal member for retaining said ribs in fixedposition, a membrane fitted over said ribs, a drivii'lg member fastenedto said normal member and an actuating means for operating said drivingmember.

7. A loud speaker according to claim 6 in which said ribs are bowed andsaid braces are attached to said ribs at approximately their mid-points.

8. A loudspeaker comprising an actuating means, a member reciprocated bysaid actuating means, a large diaphragm member attached to saidreciprocating member and a small. diaphragm member also attached to saidreciprocating member, said large diaphragm being located between saidsmall diaphragm and said actuating means.

9. A loudspeaker comprising an actuating means including a movablemember, a second member connected at one end to said movable member, anda plurality of sound wave pro ducing members connected to said secondmember.

10. A loudspeaker according to claim 9 in which said plurality of soundwave producing members are difl'erent sizes.

11. A loudspeaker comprising an actuating means, a member attached to apart of said actuating means to bereciprocated thereby, and

